4.2.1. Biodiversity

define biosphere

the inhabited part of the earth

define biome

a major life-zone characterized by the dominant plant species present

define ecosystem

the sum total of biological life (biotic factor) and non-biological components (abiotic factors) within an area which are interacting and where energy flows and nutrients cycle

define habitat

the place where an organism lives within an ecosystem

define biotic factor

a living thing, such as an animal or plant, that influences or affects an ecosystem

define abiotic factor

a non-living condition or thing, such as climate or habitat, that influences or affects an ecosystem and the organisms in it

define niche

the role of an organism within an ecosystem: how an organism affects where it lives as well as what it eats/is eaten by (position in the food chain/web)- only one species can occupy a specific niche

define population

a group of individuals of the same species occupying a given space at a given time

what is the name for the role of an organism within an ecosystem

niche

define community

a group of interacting populations in a habitat/ecosystem

define endemic

any species whose range is restricted to a limited geographical area

what is the name for any species whose range is restricted to a limited geographical area

endemic

define predator

an animal that lives by killing and eating other animals

define prey

an animal hunted or seized for food, especially by a carnivorous animal

define food chain

a linear sequence of eating and being eaten

define food web

interacting food chains

define trophic level

a stage in the food chain at which organisms obtain their food in the same general manner

define keystone species

a species that has a disproportionate effect on its environment often relative to its abundance, if this species is removed the ecosystem changes dramatically and many other species numbers change

what is a species that has a disproportionate effect on its environment often relative to its abundance, if this species is removed the ecosystem changes dramatically and many other species numbers change called

a keystone species

examples of keystone species

beavers, pollinators, mangrove trees, apex predators

define biodiversity

a measure of the variability found in the living world at the ecosystem/habitat, species and genetic levels

what are the components of biodiversity

habitat biodiversity, species biodiversity, genetic biodiversity

define habitat biodiversity

the number of different habitats present in an ecosystem

what is the nature of the environment with low habitat biodiversity

stressful and extreme with relatively few ecological niches

what is the nature of the environment with high habitat biodiversity

not stressful with many ecological niches

adaptation of species to the environment with low habitat biodiversity

few species have very specific adaptations to the environment

adaptation of species to the environment with high habitat biodiversity

many species have few species adaptations to the environment

define species biodiversity

the number of different species and the relative abundance of each species in an area

what are the parts of species biodiversity

species richness, species evenness

define species richness

the number of different species

define species evenness

the relative abundance of each species within a community

define genetic biodiversity

the variety of different alleles within the population of a species in an area

why is high genetic diversity important

high ability of the population to withstand abiotic stress

an example of genetic biodiversity

different breeds within a species e.g. dogs

examples of habitats with high habitat biodiversity

meadow, sand dunes, woodland, stream

keystone species and others present in a meadow

keystone- pollinating insects, grasses, shrubs, buttercups, nettles, dandelions, thistles

keystone species and others present in sand dunes

keystone- marram grass (binds dunes), sea holly, small mammals- mice

stability of meadows

fairly established but is changing unless managed

stability of sand dunes

young dunes are not established or stable

keystone species and others in woodlands

keystone- apex predator, trees, fungi, shrubs, insects, birds, spiders, snakes, foxes

stability of woodland

very established ecosystem

keystone species and others in a stream

keystone- salmon/perch, fish, aquatic plants, invertebrates

stability of a stream

fairly stable ecosystem

define sampling

counting/collecting a number which is representative of the target population, when the whole population is too large to be counted

types of sampling

random and non-random sampling

advantage of random sampling

avoids observer bias in data

disadvantage of random sampling

may not cover all areas of a habitat equally, species with a low presence may be missed leading to underestimate of biodiversity

types of non-random sampling

opportunistic, systematic, stratified

what is opportunistic sampling

the quadrat is placed in easiest/best place to sample a species- large bias

advantage of opportunistic sampling

easier and quicker than random sampling

disadvantage of opportunistic sampling

data may be biased, presence of large or colourful species may entice the researcher to include that species, may lead to an overestimate of its importance and therefore an overestimate of biodiversity

what is systematic sampling

samples taken at regular intervals, usually used by placing a transect to study changes in distribution of organisms/environmental gradient along a line e.g. away from a pond

advantage of systematic sampling

useful when the habitat shows a clear gradient in some environmental factor

disadvantage of systematic sampling

only species on the line or within the belt can be recorded, other species may be missed, leading to underestimate of biodiversity

what types of transects are there

line and belt

what is the difference between a line and belt transect

line has no quadrat used, belt uses a quadrat

what is stratified sampling

used for an area with different sections, each area is sampled randomly, sample size in each area is proportional to the size of the area

advantage of stratified sampling

ensures all different areas of a habitat are sampled and species are not under-represented due to the possibility that random sampling misses certain areas

disadvantage of stratified sampling

there is a possibility that this may lead to over representation of some areas in the sample e.g. disproportionate number of samples taken in small areas that look different

sampling techniques for sampling plants

frame quadrat, point quadrat

type of frame quadrats

open frame or gridded

ways of using frame quadrat to estimate abundance

frequency, percentage occurrence, percentage cover, ACFORN scale

percentage occurrence method of estimating abundance

how many squares the species occurs in, multiply by percentage of quadrat each square represents

percentage cover method of estimating abundance

estimate the % area a species covers by looking at it

ACFORN scale method of estimating abundance

a scale using descriptions to indcate occurrence of plants, Abundant, Common, Frequent, Occasional, Rare, Never

advantages of ACFORN scale

quicker, wider area can be surveyed

disadvantages of ACFORN scale

subjective, misses smaller plants

what is a point quadrat

series of pins, count plants touching pins, useful for longer vegetation, can overestimate tall thin leaved plants that touch multiple pins

what is used to identify plant species

an identification key

what methods are there for sampling animals

pitfall traps, pooters, sweep nets, quadrat, kick sampling

what are pitfall traps used for

small invertebrates living on the ground and detritivores, sampled in leaf litter or soil

how do pitfall traps work

• a hole is dug in the soil

• container is placed so top is at the level of the soil

• sides of container are steep and slippery preventing escape

• alcohol can be placed inside to prevent invertebrates from leaving

• waterproof cover stops rain filling trap or scavengers getting in

• container is left overnight for nocturnal animals

what are pooters used for

invertebrates living above the ground, sampled anywhere above ground and usually on leaves that small invertebrates are visible and accessible

how do pooters work

end of one tube is pointed close to the insect, air is sucked in pulling the insect into the chamber, filter present to prevent animals from being sucked up

what are sweep nets used for

flying insects, sampled in tall grass or crops

how do sweep nets work

net is moves across the vegetation/long grass, trapping invertebrates, must use standardised methods e.g. 2 sweeps

what are quadrats used for when animal sampling

limpets, barnacles, mussels, animals fixed in one place, slow moving

how do quadrats work when animal sampling

placed over sessile animals and the frequency counted

what is kick sampling used for

freshwater invertebrates living in mud

how does kick sampling work

kick mud and hold net down stream, standardise number of kicks

what method is used to estimate population size of animals that move

capture-mark-release-recapture

what is the process of capture-mark-release-recapture

record number of individuals of a species caught, mark and release them, allow time for animals to redistribute, recapture, record number caught and how many were marked

what can be used in capture-mark-release-recapture to estimate population size

Lincoln index

Lincoln index equation

population size= no. of individuals in 1st sample x no. individuals in 2nd sample/no. recaptured marked individuals in 2nd sample

assumptions used in the Lincoln index

• population of organisms must be closed, no migration

• time between samples must be small compared to the life span of the organism- no births/deaths

• marked organisms must redistribute completely with the rest of the population during the time between the first and second samples

• every individual has an equal likelihood of being found

• marking doesn’t affect animal in any way

• population must be large

disadvantages of estimating animal population sizes such as using photo traps, footprints, faeces or fur

weather can wash away/distort footprints, multiple people see same animal, takes time to test faeces/fur

what is Simpson’s Index of Diversity

a measure of species diversity which takes into account both species richness and species evenness, calculated by taking a sample of a plant/animal community in an area

what is a measure of species diversity which takes into account both species richness and species evenness

Simpson’s Index of Diversity

what does n represent in Simpson’s Index of Diversity

no. of individuals in a population

what does N represent in Simpson’s Index of Diversity

total number of individuals in the community

what populations are normally used in Simpson’s Index of Diversity

populations at the same trophic level

how can alleles be described

homozygous dominant, homozygous recessive, heterozygous

define homozygous dominant/recessive

the diploid condition where both alleles are dominant/recessive

define heterozygous

the diploid condition where both the dominant and the recessive allele are present

define dominant

the allele that influences the appearance of the phenotype when present in the homozygous or heterozygous condition

define recessive

the allele that only influences the appearance of the phenotype when present in the homozygous condition

what does a greater number of different alleles cause

greater gene pool/genetic diversity, increased likelihood of individuals carrying advantageous allele when faced with a selection pressure, so they can survive and reproduce, species can adapt to changes in environment so won’t become extinct

most genes are…

monomorphic- don’t have alternative alleles, ensures basic structures of individuals remains constant

define polymorphic

gene has two or more alleles at a locus e.g. dominant/recessive

how to measure genetic diversity

proportion of polymorphic gene loci= no. of polymorphic gene loci/total no. of gene loci sampled